Equine Drugs and Medications
November 28, 2011
(Equine Medications, Forney, 2001)
Useful References
The Veterinary-Client-Patient
Relationship
• VCPR – what is it?
• Defined by the American Veterinary
Medical Association (AVMA)
– The veterinarian has assumed the responsibility
for making medical judgments regarding the
health of the animal(s) and the need for medical
treatment, and the client has agreed to follow
the instructions of the veterinarian
The Veterinary-Client-Patient
Relationship
• Defined by the American Veterinary
Medical Association (AVMA)
– There is sufficient knowledge of the animal(s)
by the veterinarian to initiate at least a general
or preliminary diagnosis of the medical
condition of the animal(s)
• Examination
• Visits to premesis
The Veterinary-Client-Patient
Relationship
• Defined by the American Veterinary
Medical Association (AVMA)
– The practicing veterinarian is readily available
for follow-up in case of adverse reactions or
failure of the regimen of therapy.
• Veterinarian must maintain medical records
Medical Records
• Must comply with State and Federal Standards
• Property of the practice
– Must be retained for period determined by statute
• Information is private and can’t be released
without consent of client or by court order
• Vet is obligated to provide copies at request of
client; client should supply written release
• Vet can’t remove or copy any part of the record
without approval from practice owner
Dispensing Drugs
• In order to dispense medication, a VCPR
must exist
• AAEP Guidelines:
– Veterinarians should honor a client’s request
for a prescription in lieu of dispensing.
– Without a valid VCPR, veterinarians’
merchandising or use of veterinary prescription
drugs or their extra-label use of any
pharmaceutical is unethical and is illegal under
federal law.
The Veterinary-Client-Patient
Relationship
• Who may terminate a VCPR?
– Veterinarian  must notify client and do so
with tact and courtesy
• No ongoing medical condition
• If there is ongoing medical condition, veterinarian
must provide a referral for continuing care
– Clients may terminate relationship at any time
Safety
(Equine Medications, Forney, 2001)
Measurement Conversion Table
Conventional
Measure
Ounce (oz)
Pound (lb)
Grain
Fluid ounce (fl
oz)
Metric Measure
Multiply By
28.35
0.035
0.45
2.21
0.0154
64.8
29.57
0.03
Gram (g)
Kilogram (kg)
Milligram (mg)
Milliliters (ml)
Measurement Conversion Table
Conventional
Measure
Cup (c)
Pint (pt)
Quart (qt)
Gallon (gal)
Metric Measure
Multiply By
0.24
4.24
0.47
2.13
0.95
1.05
3.78
0.26
Liter (L)
Liter (L)
Liter (L)
Liter (L)
Extra-Label (Off-Label) Drug Use
• Using the drug in a manner other than that on the
label
– Guidance of a veterinarian
– Valid VCPR
• Examples
–
–
–
–
Using a different dose
Using a different frequency or route of administration
Using a drug for longer than is directed on the label
Treating different diseases than those indicated on the
label
– Treating a different species of animal than those
approved on the label.
Drug Compounding
•
•
•
•
Any drug manipulated to produce a dosage form
drug (other than that manipulation that is
provided for in the directions for use on the
labeling of the approved drug product).
Can be done by pharmacies
FDA in 2003: some compounded drugs are
considered “new” and must go through approval
process
Gives vets an additional tool in fighting disease
Legal vs illegal compounding
Drug Controls
• Federal Drug Administration (FDA)
• Maryland Board of Veterinary Medical Examiners
• Association of Racing Commissioners
International (ARCI)
• Federation Equestre Internationale (FEI)
• United States Equestrian Federation (USEF)
• American Quarter Horse Association (AQHA)
Drug Approval Process
• FDA definition of “drug”
Any substance, food or nonfood that is used
to treat, cure, mitigate, or prevent a disease
Any nonfood substance that is intended to
affect the structure or function of an animal
Any substance administered by injection
Drug Approval Process
• New drugs must be tested through scientific
process and shown to be effective and safe
• Effective = does what it claims consistently
and uniformly
• Safe = safe to animals and people
administering the drug; also must be safe to
environment
• Good manufacturing practices
ARCI
• Lists drugs classified according to their
abilities to influence performance
– Highest Potential for abuse/effect on
performance = Class 1
– Lowest potential for abuse/effect on
performance = Class 5
ARCI
Uniform Classification Guidelines for Foreign
Substances
• Classes 1 and 2
– Potent stimulants or depressants
– High potential to influence performance
– Little-no therapeutic uses
• Class 3
– May or may not have accepted therapeutic use but have
potential to affect performance
• Classes 4 and 5
– Therapeutic agents
FEI
ZERO TOLERANCE POLICY!!!
• Chapter V, article 1013 of Veterinary
Regulations:
“…regulations...are intended to ensure that no samples
taken from a horse during an event shall show the
presences in the horse’s tissues, body fluids or
excreta, of any substance which is a Prohibited
Substance.”
– Includes substance, metabolites of substances,
isomers and metabolites of isomers of substance
What Happened at the 2008
Olympics??
• 6 horses and riders disqualified for positive drug test
results
• Tested positive for drug, felbinac
– “Medication class A” prohibited substance applied topically for
the relief of local pain and inflammation
– Tested levels?
• "However, after doing more research on the drug and having a biochemist analyze the data, we learned that the trace amount found in
Myth's system could occur from something as distant and arbitrary as
a person using Felbinac on their knee then using a broom, then
someone else uses the broom and shakes my groom's hand, and then
my groom touches my horse. In the sampling, 14 nanograms per
milliliter were found. It takes 7500 to 100,000 nanograms per
milliliter to have an effect on a rat."
What is the FEI doing?
• November, 2008: Formed a commission on
medication and doping
– Examine current drug policy and testing procedures
• Make sure they conform to World Anti-Doping Agency (WADA)
guidelines
• Establish single protocol
– Protect the welfare of the horse
– Overcome grey areas between doping and therapeutic
medication
• Distinguish between acceptable and unacceptable practices
• New Equine Anti-Doping and Controlled Medication
Regulations (EADCMRs) established and implemented
in 2010
US Equestrian Federation
• Therapeutic Substance Provisions (Article 410)
• No foreign substance rule – includes reporting
requirements for illness and injury
– Horse may required to be withdrawn from competition
for 24 hours following administration of drug
• Thousands of prohibited substances
• Special considerations for common drugs
FEI/USEF Prohibited Substances
Substances acting on…
1. Nervous system
2. Cardiovascular system
3. Respiratory system
4. Digestive system
5. Urinary system
6. Reproductive system
7. Musculoskeletal system
8. Blood system
9. Skin (i.e.
hypersensitizing agents)
10. Endocrine system,
endocrine secretions and
synthetic counterparts
11. Anti-infectious
(including anti-parasitic)
12. Antipyretics, analgesics
and anti-inflammatory
13. Cytotoxic substances
AQHA
• Drug-free policy
– Any surgical procedure or injection of any foreign
substance or drug which could affect a horse’s
performance or alter its natural conformation or
appearance is prohibited except during surgical
procedures performed by a duly licensed veterinarian
for the sole purpose of protecting the health of the
horse.
• Uses ARCI classifications
– No Class I or II drugs allowed under any circumstances
AQHA
• January 1, 1999
– Allowed use of certain medications under stringent
guidelines:
• Be in the best interest of the horse
• Be more in line with AQHA's statement of position regarding
the welfare and humane treatment of the horse
• Help owners and exhibitors avoid disciplinary action for
inadvertently violating our previous "no presence" rule
due to improved testing technology which allows detection
of minute amounts of a drug in a horse's system even
though those amounts can have no clinical effect on the
horse
Drug Testing in Performance
Horses
• Withdrawal time
– Estimated time prior to competition that a drug
should be withdrawn
• Detection time
– Known period of time after drug administration
when it can be detected in blood, urine or body
fluid
• Clearance time
– Time it takes the horse’s body to eliminate the
drug completely
What is a “Positive”
•
Chemical identification of a substance
that violates the rules of competition
1. Screening and confirmatory tests must
result in unequivocal chemical
identification
2. Independent confirmation by a lab of
trainer’s choice
3. For substances with threshold: drug and/or
metabolites present above threshold level
Factors Affecting Withdrawal
Time
•
•
•
•
•
•
•
•
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Dose
Sensitivity of testing
Local testing procedures
pH of the urine of the horse post-race
Route of administration
Time of last meal
Frequency of drug use
Release time of drug preparation
Drug formulation
Routes - IV
(Equine Medications, Forney, 2001)
Routes - IM
(Equine Medications, Forney, 2001)
Routes - PO
(Equine Medications, Forney, 2001)
Categories of Medications
• Tranquilizers and sedatives
• Vitamins & minerals (covered in Equine
Nutrition)
• Vaccinations
• Anthelmintics (deworming)
• Hormones and anabolic steroids
• Pain-controlling drugs
• ACTH and corticosteriods
• Antibiotics
• Performance drugs and medications/Doping
Actions of Drugs in Horses
• Indications
– When is it ok to use a drug to treat a disease
• Contraindications
– When should a drug NOT be used
• Possible side effects
• Interactions with other drugs
Tranquilizers/Sedatives
• 2 categories of use in horses:
– Control of horses for surgical procedures
– Control behavior
Tranquilizers – Rules of Use
• Always check with vet re: suitability for situation
• Know horses’ sensitivities to tranqs before need
for use arises
• Avoid riding heavily tranq’ed horses
• Avoid use for training purposes
• Be aware of drug interactions
• Allow only vet to give tranqs to horses that are
injured, ill or in shock
• Never give to very young (< 1 yr) or very old
• Dose given matches dose required
Pain-Controlling Drugs
• Pain does have benefits to the horse!!
• Analgesics vs. anesthetics
– Analgesics block pain
• Narcotic – may be stimulatory in horses where
sedative in humans
• Non-narcotic/Non-Steroidal Anti-inflammatory
Drugs (NSAIDs)
– Anesthetics block all sensations
• Should be used only be vet or vet technician
ACTH and Corticosteriods
• ACTH = adrenocorticotrophic hormone
– Controls activity of the cortex and adrenal
gland
– Feedback loop
– ACTH can stimulate the horse’s adrenal glands
to produce natural corticosteriods to 10x
normal level
– Also used to test adrenal function
• Corticosteroids have an antiinflammatory effect
Indications and Side Effects
• Indications:
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–
–
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Arthritis, bursitis, tendinitis
Skin conditions
Heaves
Spinal-cord injury or inflammation
• Side-effects:
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Founder
Increased water intake  increased urine output
Sodium retention, increased excretion of K and Ca
Abnormally high blood glucose
Mood changes
Performance Drugs and
Medications
• Magic pill to make horses perform better?
• Legality of use varies state to state
• Drugs that improve respiratory tract health:
– Diuretics
• Salix/Lasix (furosemide) is perfect example
– Bronchodialators
• Drugs that act on blood system
– “Milkshakes”
– Blood doping
What is ‘blood doping?’
• Blood doping is the practice of boosting the
number of red blood cells in circulation 
enhance athletic performance
– Can improve an athlete’s aerobic capacity (VO2 max)
and endurance
• ARCI: The possession and/or use of blood doping
agents, including but not limited to those listed
below, on the premises of a facility under the
jurisdiction of the Commission is forbidden:
– Erythropoietin (“epo”)
– Darbepoetin
– Oxyglobin®
Performance Drugs and
Medications
• Drugs that act on musculoskeletal system
– Reduce pain from vigorous use
– Phenylbutazone, other NSAIDs
– Narcotics, stimulants, local anesthetics, anabolic
steroids, corticosteriods
• Drugs that stimulate the CNS
– Amphetamines
– Cocaine